From 798523973dcc93c2440932dc4dfe76fbf571f668 Mon Sep 17 00:00:00 2001 From: Sudeep Holla Date: Wed, 4 Mar 2015 17:07:57 +0000 Subject: [PATCH] usb: isp1760: fix possible deadlock in isp1760_udc_irq Use spin_{un,}lock_irq{save,restore} in isp1760_udc_{start,stop} to prevent following potentially deadlock scenario between isp1760_udc_{start,stop} and isp1760_udc_irq : ================================= [ INFO: inconsistent lock state ] 4.0.0-rc2-00004-gf7bb2ef60173 #51 Not tainted --------------------------------- inconsistent {HARDIRQ-ON-W} -> {IN-HARDIRQ-W} usage. in:imklog/2118 [HC1[1]:SC0[0]:HE0:SE1] takes: (&(&udc->lock)->rlock){?.+...}, at: [] isp1760_udc_irq+0x367/0x9dc {HARDIRQ-ON-W} state was registered at: [] _raw_spin_lock+0x23/0x30 [] isp1760_udc_start+0x23/0xf8 [] udc_bind_to_driver+0x71/0xb0 [] usb_gadget_probe_driver+0x53/0x9c [] usb_composite_probe+0x8a/0xa4 [libcomposite] [] 0xbf8311a7 [] do_one_initcall+0x8d/0x17c [] do_init_module+0x49/0x148 [] load_module+0xb7f/0xbc4 [] SyS_finit_module+0x51/0x74 [] ret_fast_syscall+0x1/0x68 irq event stamp: 4966 hardirqs last enabled at (4965): [] _raw_spin_unlock_irq+0x1f/0x24 hardirqs last disabled at (4966): [] __irq_svc+0x33/0x64 softirqs last enabled at (4458): [] __do_softirq+0x23d/0x2d0 softirqs last disabled at (4389): [] irq_exit+0xef/0x15c other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&udc->lock)->rlock); lock(&(&udc->lock)->rlock); *** DEADLOCK *** 1 lock held by in:imklog/2118: #0: (&f->f_pos_lock){+.+.+.}, at: [] __fdget_pos+0x31/0x34 Signed-off-by: Sudeep Holla Cc: Greg Kroah-Hartman Acked-by: Laurent Pinchart Signed-off-by: Felipe Balbi --- drivers/usb/isp1760/isp1760-udc.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/usb/isp1760/isp1760-udc.c b/drivers/usb/isp1760/isp1760-udc.c index 9612d7990565..19e6a172ff82 100644 --- a/drivers/usb/isp1760/isp1760-udc.c +++ b/drivers/usb/isp1760/isp1760-udc.c @@ -1191,6 +1191,7 @@ static int isp1760_udc_start(struct usb_gadget *gadget, struct usb_gadget_driver *driver) { struct isp1760_udc *udc = gadget_to_udc(gadget); + unsigned long flags; /* The hardware doesn't support low speed. */ if (driver->max_speed < USB_SPEED_FULL) { @@ -1198,7 +1199,7 @@ static int isp1760_udc_start(struct usb_gadget *gadget, return -EINVAL; } - spin_lock(&udc->lock); + spin_lock_irqsave(&udc->lock, flags); if (udc->driver) { dev_err(udc->isp->dev, "UDC already has a gadget driver\n"); @@ -1208,7 +1209,7 @@ static int isp1760_udc_start(struct usb_gadget *gadget, udc->driver = driver; - spin_unlock(&udc->lock); + spin_unlock_irqrestore(&udc->lock, flags); dev_dbg(udc->isp->dev, "starting UDC with driver %s\n", driver->function); @@ -1232,6 +1233,7 @@ static int isp1760_udc_start(struct usb_gadget *gadget, static int isp1760_udc_stop(struct usb_gadget *gadget) { struct isp1760_udc *udc = gadget_to_udc(gadget); + unsigned long flags; dev_dbg(udc->isp->dev, "%s\n", __func__); @@ -1239,9 +1241,9 @@ static int isp1760_udc_stop(struct usb_gadget *gadget) isp1760_udc_write(udc, DC_MODE, 0); - spin_lock(&udc->lock); + spin_lock_irqsave(&udc->lock, flags); udc->driver = NULL; - spin_unlock(&udc->lock); + spin_unlock_irqrestore(&udc->lock, flags); return 0; } -- 2.20.1